Global kinetic modeling of the intrabinary shock in spider pulsars

蜘蛛脉冲星双星内激波的全局动力学模型

• 批准号: 2307202
• 负责人: Lorenzo Sironi
• 金额: $ 52.77万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2307202&HistoricalAwards=false
• 关键词: Global; kinetic; modeling; intrabinary; shock

Among the most fascinating astrophysical objects are the “spider pulsars,” which are a particular type of very rapidly-rotating, extremely compact neutron stars in a binary system. Spider pulsars, which are classified as either Redbacks (RBs) or Black Widows (BWs), are in tight binary orbits with a low-mass stellar companion. The pulsar emanates an intense relativistic wind. When impacting on the companion star, the wind exacerbates ablation and mass loss of the companion, which is then “devoured” by the pulsar wind --- hence, the evocative name of these systems. A research team at Columbia University will use state-of-the-art computer simulations to better understand spider pulsars, and astrophysical shock waves in general. The lead researcher will also design a new course, “Back-of-the-envelope physics, astronomy, and beyond," to introduce students in the Columbia Bridge to Ph.D. scholars program to the art of looking at reality with quantitative eyes, using personal experience and prior knowledge as a guide to drawing order-of-magnitude conclusions, and thus to being prepared to make decisions that are grounded in quantitative reasoning.The relativistic pulsar wind consists of toroidal stripes of opposite magnetic field polarity, separated by current sheets of hot plasma. The wind terminates in a strong shock, where the ram pressure of the pulsar wind is balanced by the companion wind or its magnetosphere. The intrabinary shock may be an efficient site of particle acceleration, which would then explain why X-ray and gamma-ray lightcurves of spider pulsars are often modulated on the orbital period. Therefore, the scrutiny of BWs and RBs can help uncover the largely unknown physics of pulsar winds in millisecond pulsars, and aid in understanding where the transition occurs from a Poynting flux-dominated to a particle-dominated flow. This project will involve first-principles global kinetic Particle-In-Cell simulations of the intrabinary shock in spider pulsars, so one can simultaneously capture the microscopic physics of magnetic field dissipation, particle acceleration and ensuing emission, as well as the global morphology and curvature of the shock and the resulting macroscopic flow dynamics. While the main focus is on spider pulsars, the question of particle acceleration in magnetically-dominated striped shocks is of profound relevance to the physics of Poynting-flux-dominated relativistic outflows in other systems, like jets of active galactic nuclei and gamma-ray bursts. This award advances the goals of the Windows on the Universe Big Idea.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

其中最迷人的天体是“蜘蛛星”，这是一种特殊类型的非常快速旋转，非常紧凑的中子星在一个双星系统。 蜘蛛星，被分类为红背星（RB）或黑寡妇星（BW），与一个低质量的恒星伴星处于紧密的双星轨道上。脉冲星散发出强烈的相对论风。当撞击伴星星星时，风加剧了伴星的烧蚀和质量损失，然后被脉冲星风“吞噬”--因此，这些系统的名字令人回味。 哥伦比亚大学的一个研究小组将使用最先进的计算机模拟来更好地了解蜘蛛星云和一般的天体物理冲击波。 首席研究员还将设计一门新的课程，“信封后面的物理学，天文学和超越”，介绍学生在哥伦比亚桥博士。学者们的编程艺术是用定量的眼光看待现实，利用个人经验和先验知识作为指导，得出数量级的结论，从而准备做出基于定量推理的决定。相对论性脉冲星风由磁场极性相反的环形条纹组成，由热等离子体的电流片隔开。风以强烈的激波结束，脉冲星风的冲压压力被伴风或其磁层平衡。双星内部的激波可能是粒子加速的有效场所，这就解释了为什么蜘蛛星的X射线和伽马射线光变曲线经常被调制在轨道周期上。因此，对BW和RB的仔细研究可以帮助揭示毫秒脉冲星中脉冲星风的基本未知物理学，并有助于理解从坡印廷通量主导到粒子主导的转变发生在哪里。 该项目将涉及第一原理的全球动力学粒子在细胞内模拟的双胞胎内冲击在蜘蛛星系，所以人们可以同时捕捉磁场耗散，粒子加速和随之而来的发射，以及全球形态和曲率的冲击和由此产生的宏观流动动力学的微观物理。 虽然主要的焦点是在蜘蛛星系上，但磁主导的条纹激波中的粒子加速问题与其他系统中坡印廷通量主导的相对论外流物理学有着深刻的相关性，如活动星系核的喷流和伽马射线爆发。 该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。